Note: Descriptions are shown in the official language in which they were submitted.
7~;
The present invention relates to a time division
multiplex remote control system and, more particularly,
relates to an interruption handling system capable of
rapidly handling an interruption when a supervisory input
in a terminal causes a change.
The present invention will become more apparent
from the following de-tailed description of the preferred
embodiment oE the present invention when taken in con-
junction wi-th the accompanying drawings, in which:-
Fig. 1 is a schematic diagram showing a conven~
tional time division multiplex remote control system;
Fig. 2 is a diagram illustrating a format ofa transmission signal used in the system shown in Fig.
1 ;
Fig. 3 is a schematic diagram showing a time
division multiplex remote control system embodying the
present invention;
Fig. 4 shows one example of a format of signals
used in the time division multiplex remote control system
embodying the present invention, wherein Fig. 4(a~ shows
an example of a transmission signal and Fig. 4(b) shows
a signal returned from a terminal;
Fig. 5 is a block diagram showing a structure
o~ a terminal shown in Fig. 3;
Fig. 6, which appears on the same sheet as Figs.
1 and 2, is a waveform showing an example of a xeply signal
from a terminal;
Fig. 7, which appears on the same sheet as Fig.
5, shows a more detailed circuit diagram of a change-of-
supervisory input detecting circuit shown in Fig. 5;
Fig. 8 shows a detailed circuit of a signal re-
ceiving portion shown in Fig. 5;
Fig. Y, which appears on the same sheet as Figs.
l and 2, is a schematic block diagram showing a central
controller;
Fig. lO is a Elow chart showing an operation
performed in a cen-tral controller;
9~i7~S
Fig. 11 is a flow chart showing an operation
performed in a terminal;
Fig. 12A is a waveform for explaining a manner
of returning an interruption request signal;
Fig. 12B shows an example of a circuit imple-
menting the manner of returning shown in Fig. 12A;
Fig. 12C is a waveForm for explaininy an opera--
tion of the circuit shown in Fig. 12A; and
Fig. 13 is a flow chart showing a modiEication
of an operation performed in a central controller.
Fig. 1 shows a schematic block diagram showing
an entire time division multiplex remo-te control system
of the above-mentioned type. Such a remote control system
incluaes a central controller 1 and a plurali-ty oE ter-
minals 2 having respective inherent addresses connectedto a signal line 3 A transmission signal including in-
herent address data is transmitted from the central con-
troller 1 so that one of the terminals 2, corresponding
to the inherent address, is accessed, and the communica-
tion of data such as control data and supervisory datais made between the central controller 1 and -the accessed
terminal 2. For example, in a modern building, terminals
2, 2, ... are provided in each of the rooms, respectively,
the terminals 2, 2, ... applying control information to
an object to be supervised, such as a lamp and a wall type
switch in each room and also supervising a change of a
supervisory input from each of the objects to be super-
vised. For example, assuming that the object to be super-
vised ts a wall type swi-tch and the switching of the lamp
is made by an on/off actuation of -the wall type switch,
the change from the off to the on in the wall -type switch
is detected as a change of a supervisory input by the ter-
minal 2 when the wall type switch is switched on for the
purpose of lighting. The data as to the change of the
supervisory input, which is supervisory data, i5 returned
to the central controller 1 as a reply signal when the
corresponding -terminal 2 is accessed through polling from
the central controller. The central controller 1 receives
the supervisory data and then sends to the terminal 2 con-
trol data necessary Eor lighting a corresponding lamp.
The terminal 2 accep-ts the control data and lights the
lamp.
Fig. 2 shows an example of a format of a trans-
mission signal used in a conventional time division multi
plex remote con-trol system. The transmission signal in-
cludes a start signal or a start signal field ST, an ad-
dress signal or an address signal region AD for transmitting
address data of a terminal, a control signal or a control
signal region CTR for transmitting control data, and a
reply signal standing-by period defining signal or a reply
signal standing-by period defining signal region RW for
defining timing period receiving a reply signal from -the
addressed terminal. The transmission signal is in the
form of a bipolar pulse-width demodulated signal.
Now, referring to Figs. 1 and 2, an operation
of the conventional time division multiple~ remote control
system will be briefly described. First, the central con-
troller 1 sequentially and cyclically accesses the -terminals
2. To this end, each of the terminals is sequentially
polled by sequentially changing the address data included
in the transmission signal shown in Fig. 2. If and when
the terminal 2 receives a transmission signal including
address data coinciding with i-ts own inherent address,
-the -terminal 2 accep-ts the con-trol da-ta included in the
transmission signal and outputs the control output CS to
control a load associated with the terminal and also sends
out to the central controller 1 supervisory data, as a
reply signal, based on a supervisory input SS during the
period se-t by a reply signal standing-by period defining
signal RW.
As described in the foregoing, sincer in this
type of conventional time division multiplex remote control
~:L~7~
system, each of the terminals 2 is sequentially accessed,
the time necessary for accessing all of the terminals 2,
2, ... becomes longer as the number of the terminals is
increased. Accordingly, even if a change of the super-
visory input SS occurs immediately after a certain terminal2 is polled, the -terminal 2 will be responsive at the time
oE the next polling after all of the remaining terminals
are polled, which means that the rate of the response is
very slow. For example, considering the above-described
wall type switch, a non-practical situation occurs where
a lamp is lighted only after 5 to 10 seconds following
actuation of the switch for the purpose of lighting the
lamp. In addition, assuming that an object to be super-
vised is a smoke sensing apparatus, for example, even if
the smoke sensing apparatus senses smoke and the terminal
2 detects the change of the supervisory inpu-t SS, the res-
ponse thereto may possibly become unduly slow, due to the
order of the polling, which is, of course, not practical.
More particularly, the frequency of accessing
the terminals 2 for frequently detecting changes of the
supervisory input is low, since the teL in~ls 2 detecting
the change of the supervisory input and other terminals
2 rarely detecting the change of the supervisory input
are uniformly and sequentially accessed for the purpose
o~ checking the status of the supervisory input SS. Fur-
thermore, since all of the terminals are cyclically ac-
cessed, the frequency of accessing a single one of the
terminals 2 is necessarily decreased if the number of the
terminals 2 is increased.
The present invention is directed to a -time
division multiplex remote control system for da-ta trans-
mission between a central controller and a plurality of
addressable remote terminals coupled to the central con-
troller through a signal line. The central controller
includes transmission signal generating means for genera-
ting a transmission signal to be transmitted and trans-
mitting means for transmi-tting the transmlssion signal
generated by the transmission signal generating means.
The transmission signal comprises a terminal identifying
information for identiEying one of the plurality of ter-
minals whlch is to receive the transmission signal to betransmitted, control information indicating a control to
be made in the terminal, and a reply signal standing-by
period defining signal for defining a period or a -timing
Eor receiving a reply signal returned from the terminal
identified by the terminal identifying information. The
cen-tral controller fur-ther includes receiving means for
receiving a signal sent by the terminals and control in-
formation producing means responsive to the received reply
signal for producing necessary control information. In
addition, each of the plurality of the terminals includes
store means for storing identifying information identify-
ing the corresponding terminal, receiving means for re-
ceiving the -transmission signal being transmitted from
-the central controller, control information accepting means
responsive to the receiving means for accepting -the control
information included in the transmission signal when the
received terminal iden-tifying information coincides with
its own identifying information stored in the storing means,
reply signal transmitting means responsive to the receiving
means for transmitting a reply signal in response to the
reply signal standing-by period defining signal included
in the received transmission signal when the received ter-
minal identifying information coincides with the identi-
fying information stored in the storing means, change-
of-supervisory input cletecting means for detecting the
change oE the supervisory input of an object to be con-
trolled, which the terminal supervises, interruptior. re-
quest signal generating means for generating an interrup-
tion request signal in response to the change-of-supervisory
input detecting output from the change-of-supervisory input
detecting means, and interruption request signal -transmit-
ting means for transmit-ting the interruption request sig-
nal generated in the interruption request signal genera-
ting means at the timing other than the reply signal trans-
mi-tting timing.
In accordance with a preferred embodiment o~
the present invention, the plurality of terminals are
divided into a plurality of groups each including a pre-
determined plurality of the terminals. The terminal iden-
tifying information comprises group identifying informa-
tion identifying a group in which a respective one of the
terminals is included and individual terminal identifying
information for identifying individually the -terminal in-
cluded in the group. The central controller fur-ther in-
cludes group accessing mode signal generating means res-
ponsive to the interruption request signal transmittedby the interruption request signal transmitting means in
the respective terminal for generating a group accessing
mode signal for specifying a mode accessing the terminal
for each group. The -transmission signal transmitting means
sequentially transmits the group address as terminal iden-
tifying information. As a result, in the case where an
interruption request signal is genera-ted, a plurality of
-terminals are accessed for each group, so that the par-
ticular terminal generating the interruption request signal
can be rapidly accessed.
In accordance with the preferred embodiment of
-the present invention, the reply signal transmitting means
in the terminal transmits as a reply signal individual
identifying information identifying the terminal when the
group identifying inEormation received by the -terminal
coincides with the group identifying information stored
in the store means. In addition, the transmission signal
transmitting means in -the central controller transmits
as terminal identifying information the received individual
identifying information when the controller receives the
individual identifying informa-tion as a reply signal.
, ~
,. ~
In the preferred embodiment of the presen-t in-
vention, the transmission signal from the transmission
signal -transmi-tting means in the cen-tral controller com-
prises an in-terrup-tion request signal standing-by period
defining signal for defining an interruption request signal
standing-by period for receiving the interruption request
signal. The interrup-tion request signal transmitting means
transmits the interruption request signal during the
standing-by period in response to the interruption request
signal standing-by period defining signal from the trans-
mission signal transmitting means.
Also in the preferred embodiment of the present
invention, the interruption request signal standing-by
period defining signal is divided into a plurality of sub-
periods corresponding to the plurality of groups of theterminals. The interruption request signal is sent out
during the subperiod corresponding to the group identifying
information for the group which the terminal having gen-
erated the interruption request signal belongs to. As
a result, the group which the terminal having generated
the interruption request signal belongs to can be easily
identified.
The individual identifying information sent out
as the reply signal in the preferred embodiment is coded
information of a plurality of bits wherein a signal of
a single bit is represented by a combination of one pulse
having a longer pulse wid-th and the other pulse having
a shorter pulse width or a combination of one pulse having
a shorter pulse wid-th and the o-ther pulse having a longer
pulse width. The central controller detects a combination
of two pulses having a longer pulse wid-th in each bit of
the individual identifying information returned as the
reply signal and hence can detect that there exists in
a single group more than two terminals which have been
sending out an in-terruption request signal. Furthermore,
if and when such combination of two pulses having a longer
7~
pulse width is detected, possible addresses are evaluated
based on the bit position or positions where such combina-
tion or combinations are detected, so that only the ter-
minals corresponding to the possible addresses can be
polled.
Fig. 3 is a block diagram showing a schematic
structure of the time division multiplex remote control
system of the preferred embodiment of the present inven-
tion. As in the above~described conventional system, a
plurality of terminals 2 are connec-ted to a central con-
troller 1 through a signal line 3. As far as this con-
nection is concerned, it is the same as that in Fig. 1.
However, in the present case the plurality of terminals
are divided into a plurality of groups Gl, G2, G3 ... Gn.
For example, assuming that there are 256 terminals in the
system, these terminals are divided into 16 groups, each
group including 16 terminals. Eight bits are used for
specifying identi~ying information, that is, an address
of a terminal. Of these 8 bits, the four most signifi-
cant bits are used for identifying a particular group andthe four least significant bits are used for individually
identifying a terminal in that particular group. For ex-
ample, the four most significant bits of the addresses
of 16 terminals included in the first group Gl are all
"0000". On the other hand, regarding the remaining four
least significant bits, "0000" to "1111" are assigned to
the four least significant bi-ts, respectively, for each
of 16 terminals included in the group. For example, the
address of the first -terminal included in the first group
30 Gl is represented by "00000000", the second terminal is
represented by "0000001", the third terminal "0000010"
and so on. In the second group, "0001" is assigned to
all of the four most significant bits for all of the 16
terminals included in the second group and the four least
significan-t bits, "0000" to "1111" are assigned to the
individual terminals within the second group. Thus, each
.
7q~i
of the terminals has a particular address so that each
of the terminals can be individually identi~ied and also
can be identified as to its group.
Fig. ~ta) shows an example of a format of a trans-
mission signal transmit-ted from a central controller used
in a time division multiplex remote control system embody-
ing the present invention. The format of this transmission
signal is diEferent from the conventional transmission
signal format shown in Fig. 2 in the Eollowing respects.
More particularly, an interruption request signal standing-
by period defining signal IRS for defining a period of
timing for accepting an interrup-tion request signal IRQ
(Fig. 4(b)) is providea prior to a start signal ST, and
a mode designating signal M is also provided between the
start signal ST ana an address signal AD, the mode designa-
ting signal M designating either an individual terminal
accessing mode for individually accessing one of the ter-
minals or a group accessing mode for accessing one of the
groups of terminals when an interruption is requested.
More specifically~ a field for the mode designation com-
prises four bits and hence an ACK mode can be also defined
other than by the two above-described modes. The ACK mode
will be described with reference to Fig. 10.
As shown in Fig. ~, a transmission signal ~ormat
used in the present embodiment comprises the interruption
request signal standing-by period defining signal IRS,
a start signal ST, a mode designating signal M, the ad-
dress signal AD, the control data CTR and the reply signal
standing-by period de~ining signal RW. The central con-
troller 1 transmi-ts such transmission signals. Meanwhile,
al-thouyh, in the embodiment of Fig. ~, the interruption
request standing-by period defining signal IRS is speci-
fically provided, it will be clear ~rom the subsequent
description that, basically, such an interruption request
signal standing-by period is not necessarily provided if
an interruption request signal is adap-ted to be received
~6;7q:~
-- 10 --
during a period other than the reply signal standing-by
period.
Prior to a detailed description of the present
embodiment, a brief operation will be described with refer-
ence to Figs. 3 and ~ for the purpose of explaining thebasic concep-t of the present embodiment.
Usually, the central controller 1 individually
and sequ~ntially accesses each of the terminals 2, just
as the conventional time division multiplex remo-te control
system. Now, it is assumed that when a par-ticular terminal
22 included in the second group G2 is being polled, another
terminal 21 included in the same second group sends out
an interruption request signal IRQ to the central control-
ler 1. Since the interruption re~uest signal IRQ from
the terminal 21 is sent out during an interruption request
signal standing-by period in the embodiment of Fig. 4,
the central controller 1 can receive the interruption re-
quest signal IRQ immediately. Thereafter, in the central
controller 1, the mode designating signal M in the trans-
mission signal format is set to designate a group accessingmode. As a result, af-ter the interruption request is re-
ceived by the cen-tral processor 1, addressing of the ter-
minals is made fcr each group, in the order of the firs-t
group Gl, the second group G2~ the third group G3, ... In
the accessing of the second group, the central controller
1 detects that one of the terminals included in the second
group is sending out an interruption request signal, since
the terminal 21 included in the second group is sending
out an interruption request signal. Thereaf-ter, in the
central controller 1, the mode designating signal M is
set to designa-te an individual terminal accessing mode
again and then the terminal 21 included in the second group
is accessed in an individual accessing mode. As a result,
it is specified that a particular terminal 21 is sending
out an interruption request signal and hence necessary
control information is sent out to the terminal 21.
t;'7~'5
With the above-described basic concept in mind,
a more detailed description of the present embodiment of
-the present invention will be described.
Fig. 5 is a schematic block diagram showing a
structure of one of the terminals 2 of Fig. 3. The ter-
minal 2 includes a transmission signal receiving circuit
51 for receiving a transmission signal transmitted from
the central controller 1 through a signal line 3. The
signal receiving circuit 51 receives a serial transmission
signal in a format shown in Fig. 4 and effects a series-
parallel conversion of the received transmission signal,
so that a mode signal M, an address signal AD, a control
signal CTR and a timing signal, which is produced based
on the start signal ST, the interruption request signal
standing-by period defining signal IRS and the reply signal
standing-by period defining signal RW, are withdrawn. The
mode signal M from the signal receiving circuit 51 is ap-
plied to a mode determining circuit 53. The mode deter-
mining circuit 53 is responsive to the mode signal M for
applying an address determination enabling signal for en-
abling determination of address in an address de-termining
circuit 54. For example, assuming that the mode signal
M is a signal for designating an individual terminal ac-
cessing mode, the corresponding address determination en-
abling signal enables an address determination or comparisonof the received address signal inputted to the address
determination circuit 5~ and address information stored
in an address setting and s-toring means 59 which is
described subse~uently, and assuming that the mode signal
M is a signal for determining a group accessing mode, the
enabling signal enables the determination or comparison
of the address portion in the received address signal iden-
tifying a group, for example, -the four most significant
bits of the address and the address portion in the address
information stored in the storing means 59, for example,
the Eour most significant bi-ts. The address determining
~L~
circuit 54 is a comparator circuit, for example, which
compares an address signal ou-tputted from the signal re-
ceiving circuit 51 with address information from -the ad-
dress setting switch or address se-tting and storing means
59 on a bit by bit basis. As described in the foregoing,
in the case of an individual terminal accessing mode, all
of the bits in -the address information are compared and
in the case oE a group accessing mode, all the bits oE
only the address portion identifying a group are compared.
The address setting switch or address store 59 applies
all of the bits of an address stored therein to the ad-
dress determining circuit 54 and also applies to a signal-
to-be-replied output circuit 57 only an address portion
of the least significant bits for determining an individual
address of the terminal, for example, information of the
four least significant bits. If and when all of the bits
compared coincide with each other, that is, when the re-
ceived address by the terminal coincide with the address
s-tored 59 included in the terminal in an individual acces-
sing mode, the address determining circuit 54 applies acoincidence output to an output latch circuit 55. If and
when a result of comparison is a coincidence in a group
accessiny mode, that is, the four most significant bits
coincide with each other, a coincidence output is applied
to the signal-to-be-replied outputting circuit 57.
The control signal CTR from the signal receiving
circui-t 51 is coupled to the output latch circuit 55. The
output latch circuit 55 latches the control signal CTR
Erom -the signal receiving circui-t 51 in response to a
coincidence output from the address determining circuit
54 so that the circuit 55 supplies the control signal to
a load 60 such as a lamp.
In addi-tion, the terminal includes a supervisory
input detecting and latch and change-of-supervisory input
detecting circuit 56 which de-tects a supervisory input
SS from a supervisory inpu-t circuit 61, such as a wall
.
type switch or the like, to latch supervisory input data
and detects the change of the supervisory input. The
signal-to-be-replied output circuit 57 is responsive to
a determination output from the mode determining circuit
53 and a timing signal from the signal receiving circuit
51 (the timing signal is generated in response to a reply
signal standing-by-period defining signal included in a
transmission signal received) for returning as a reply
output the supervisory input data latched in the latch
circuit 56 through the signal line 3 to the central con-
troller 1. In the case of the group accessing mode, the
address information o~ the four least significant bits
stored in the store 59 is sent out as a reply signal to
the central controller 1 through the signal line 3 from
the output circuit 57, in response to the timing signal
from the above-described signal receiving circuit 51, a
coincidence output of the four most significant bits from
the address determining circuit 54 and a set output from
a subsequently described interruption flag 58.
Furthermore, in the case where the supervisory
input SS from the supervisory input circuit 61 changes,
the supervisory input detecting and latch and change-of-
supervisory input detecting circuit 56 detects the super-
visory input data and latches the same and also applies
a detection outpu-t of the change of the supervisory input
to the in-terruption flag 58. The interruption flag 58
is set in response -to the detection output of the change
of the supervisory input from the circui-t 56. The set
output from the interruption flag 58 is sent ou-t to the
central controller 1 from the signal-to-be-replied output
circuit 57 through a signal line in response to a timing
signal from the signal receiving circuit 51 (the timing
signal is genera-ted in synchronization wi-th the inter-
ruption reques-t signal standing-by period defining signal
included in a transmission signal). As a result, the in-
terruption re~uest signal IRQ is sent to the central con-
. .
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- 14 -
troller 1 during the interruption request signal receiving
period in the controller 1.
Meanwhile, the mode determining circuit 53 gen-
erates a reset signal for resetting -the interruption flag
58 and the circuit 56 when the circuit 53 determines an
ACK mode.
As described in the foregoing, although all of
the terminals included in a particular group accessed in
a group accessing mode are accessed at the same time, only
the or each terminal 2 having outputted an interruption
reques-t signal IRQ, that is, in which the interruption
flag 58 included therein is set, sends out as a reply sig-
nal the four least significant bits of its own address
stored in the store to the central controller 1 during
the period receiving a reply signal standing-by period
defining signal RW. One example of sending the data of
the four least significant bits will be described in the
following. For example, the logical data of each of the
four least significant bits in the address is formed by
a coded signal of 2 bits. For example, if the logical
value is "1", the corresponding code signal is "10" and
if the logical value is "0" then the code signal is "01".
Accordingly, the aadress data represented by 4 bits of
the four least significant bits which is "0000" is formed
25 as a reply signal RS of 8 bits of "01" "01" "01" "01".
Similarly, the address data of the Eour least significant
bits which is "1100" is formed as a reply signal of 8 bits
of "10" "10" "01" "01". In this case, the logical value
"1" in a reply signal RS is represented by a pulse having
a longer pulse width and the logical value "0" in a reply
signal RS is represen-ted by a pulse having a shorter pulse
width. Therefore, if a value in a predetermined bit of
the four least significan-t bits in the address data is
"1", the reply signal RS corresponding thereto is a signal
of 2 bits of "10" as shown in Fig. 6(a). ~n the other
hand, the value in a predetermined bit in the address data
~.
~t;'~
is "0", the reply signal RS corresponding thereto becomes
a signal of 2 bits of "01" as shown in Fig. 6(b). Accor-
dingly, if and when these signals are sent out simultane-
ously, the reply signal RS corresponding to the above-
described predetermined bi-ts, sent out to the signal line
3 becomes a signal of "11" as shown in Fig. 6(c). Since
the code signal of "11" does not indicate the logical values
"1" and "0", the central controller 1 can determine or de-
tect tha-t the reply signals are sent out from more than
two terminals 2 included in a group by detecting such code
signal.
Fig. 7 is a circuit showing in detail a super-
visory input detecting and la-tch and change-of-supervisory
input detecting circuit 56 shown in Fig. 5. The circuit
56 includes a latch circuit 561 receiving a supervisory
input from a supervisory input circuit 61 and latching the
state of the supervisory input. The supervisory input is
connected to a D input terminal of a D type flip-flop 562
and also is applied to one input o~ an EXCLUSIVE OR gate
563. A sampling clock CKO is connected to a clock terminal
of the D type flip-flop 562. A Q output of the D type flip-
flop 562 is connected to the other input of the EXCI.USIVE
OR gate 563. Thus, a change of a supervi.sory input is de-
tected. If the supervisory input signal changes, the
EXCLUSIVE OR gate 563 outputs a logical "1" signal in res-
ponse to -the Q output from the D type flip-flop 562 and
the supervisory input signal SS. The "1" output from the
gate 563 is applied to one input of an AND gate 565 through
an OR gate 564. A sampling clock CKl is supplied to the
other input oE the AND gate 565. An output from the AND
gate 565 is ~pplied as a detecting output of the change
oE supervisory input to a set input terminal oE an RS flip-
flop constituting the interruption flag 58. Correspondingly,
an interruption flag set signal is withdrawn from -the Q
output in -the interruption Elag 58. Although only one super-
visory input was described, it can be easily understood
~.
that other supervisory inputs can also be detected in the
same manner as described in the foregoing. Such detected
outputs are appli~d to the AND gate 565 through the OR gate
564 to set the RS fli.p-flop 58 at the timing of the sampling
clock signal CKl.
Fig. 8 is a block diagram showing the details
of the signal receiving circuit 51 in Fig. 5. A trans-
mission signal transmitted -through a signal line is applied
to a D inpu-t terminal oE a D type flip-flop 511 and also
applied to one input of an EXCLUSIVE OR ~ate 512. A clock
signal CKl is applied to a clock input terminal of the D
type flip-flop 511. A Q output of the flip-flop 511 is
connected to the o-ther input of the EXCLUSIVE OR gate 512.
As a result, the change of the transmission signal is de-
].5 tected just the same as the structure of the D type flip-
flop 562 and the EXCLUSIVE OR gate 563 in Fig. 7. If the
change of the transmission signal is detected, the "1" out-
putted from the EXCLUSIVE OR gate 512 is applied to a D
terminal of the second D type flip-flop 513. A clock ter-
minal CK of the D type flip-flop 513 is coupled to the clock
CKl. The Q terminal of the flip-flop 513 is connected to
a CK terminal of a shift register 514, the Q terminal thereof
being connected to an inverted input of an AND gate 515.
The other inverted input of the AND gate 515 is coupled
to the clock CKl. An output from the AND gate 515 is con-
nected to a reset input of the counter 516. A cloclc CK0
from the clock source 52 is applied to a count input of
the counter 516. If a value counted by the counter 516
exceeds a predetermined -threshold value, the "1" output
is supplied to -the shif-t register 514 from the Qn terminal
of the coun-ter 516. In -the above-described structure, the
change of each of the pulse signals constituting a trans-
mission signal is detected by the first D type flip-flop
35 511 and the EXCLUSIVE OR gate 512. The detected signal
is applied to a clock terminal of the shift register 514
through the second D type flip-flop 513. While a next de-
, ~
~.
tected signal is being applied after the counter 516 is
reset by the previously detected signal, the counter 516
counts the n~lmber oE clocks CK0 supplied, and if the counted
value thereof already exceeded a predetermined value of
counts, the "1" is applied to the shift register 514 from
the Qn -terminal of the counter 516, so that the shift
register 514 stores the current transmission signal as
"1". If and when the value counted hy the counter 516
is less than the predetermined threshold value, "0" is
applied to the shif-t register 514, so that the shift
register 514 stores a corresponding portion of a current
transmission signal as "0". The counter 516 is reset by
the output from the AND gate 515 simultaneously with storing
in the shift register 514, so that a measure of the pulse
width or the next signal is prepared. Thus, a serial trans-
mission signal in such a format as shown in Fig. 4 is
sequentially shifted and stored in the shift register 514,
so that series parallel conversion of the transmission
signal is made.
Fig. 9 is a schematic block diagram showing a
structure of a central controller 1. A reply signal RS
or an interruption request signal IRQ from a terminal is
received in a replied signal receiving circuit 91 and then
~pplied to a control 92. The control 92 is structured
by a microprocessor or a microcomputer, for example. Atransmission signal generating circuit 93 generates a trans-
mission signal in response to a control signal from the
con-trol 92. The transmission signal generated is trans-
mitted to each of -the terminals through a signal line 3
by a transmission signal transmitting circuit 94.
Fig. 10 is a flow chart for explaining an opera-
-tion of a central controller 1 and Fig. 11 is a flow chart
for e~plaining an operation oE a terminal 2. Referring
to Figs. 10 and 11, an operation of the present embodiment
in accordance with the present invention will be described.
11~ First, -the usual operation is assumed. More
- 18 -
particularly, it is assumed that each of the terminals
is polled by a central controller and no particular change
of a supervisory input occurs.
Once an operation starts, in the central con-
troller 1, a mode signal M (Fig. 41 is set to the indi-
vidual terminal accessing mode and an address corresponding
to the firs-t terminal oE all oE the terminals or an address
corresponding to the firs-t terminal of the terminals in
a predetermined order is se-t as an address signal and also
a control signal corresponding thereto is set. Similarly,
in the step Sl, the transmission signal including the start
signal, the interruption request signal standing-by period
defining signal and the reply signal standing-by period
defining signal as shown in Fig. 4 is produced and trans-
mitted. On the other hand, on the terminal side, in Fig.11, after a transmission signal is received in the step
S101, it is determined in the step 102 whether a mode
designating signal in -the received transmission signal
designates an individual accessing mode or not. In this
case, the mode is an individual accessing mode and thus
the program proceeds to the s-tep 103 wherein an address
included in the received transmission signal is compared
with an address of the terminal which just received the
transmission signal. If and when both addresses coincide
with each other, the program proceeds to the step 104
wherein it is determined whether an interruption Elag is
set. In the state we now assume, the interruption flag
has not yet been se-t and thus in the next step S105, an
interrup-tion status bit included in a reply signal (the
reply signal is usually s-tructured by bits indicating super-
visory data plus a status bit indicating an interruption
status and a parity bit indicating a parity) is set to
zero. Thereafter, in the step S106, a reply signal com-
prising a supervisory input and interruption status in-
formation is sent out. Thereafter, the program proceeds
to the s-tep S107 wherein the con-trol data included in
-- 19 --
the receivea transmission signal is accepted and is out-
pu-tted to the object to be supervised. Then, a super-
visory input is checked in -the step S108 and it is deter-
mined whether there is a change of a supervisory input
in the step S109. In the situation we now assume, there
is no change of supervisory input and hence the sequence
xeturned to -the start and the steps already described are
repeated.
If the address included in the transmission signal
received by the terminal does not coincide with the actual
address stored in the terminal, the program is returned
to the start through the s-teps S103 to S108 and S109.
~ 2) Now it is assumed that a change o~ supervisory
input is detected when a terminal is polled in an indivi-
dual accessing mode.
In this case, in the step S108, the change ofthe supervisory input is detected and in the step S109,
it is determined that change of supervisory input occurs.
Accordingly, the program proceeds to the step SllO wherein
an interruption flag is set. Thereafter, in the step Slll,
it is determined whether it is a timing when an inter-
ruption request signal IRQ is to be sent out. More particu-
larly, it is determined whether now is an interruption
request signal standing-by period in the transmission signal.
If and when such timing comes, the program proceeds to
the step 112 wherein the interruption request signal IRQ
is sent out through a signal-to-be-replied outputting cir-
cuit.
The interruption reques-t signal IRQ sent out
from the terminal is received in the central controller.
Again referring to Fig. 10, the interruption request signal
sent from the terminal is detected in the step S3 and there-
aEter, in the step S4, it is determined whe-ther there is
an interrup-tion reques-t signal IRQ. Since an interruption
request signal IRQ has already been received, the program
proceeds to the step S5 wherein each of the groups of ter-
6~
- 20 -
minals is accessed for each group in the group accessing
mode. For example, in the case where there are 16 groups,
each group including 16 terminals, a transmission signal
is transmitted to each group from the address "0000" to
"1111" in the four most significant bits. In the step
S6, it is determined whether address data of the four least
significant bits is returned from a group for each polling
of each group. If and when there is no reply, the program
returns to the s-tep S5 wherein an address in the four most
significant bits is incremented by 1. In such a way, all
of the 16 groups are accessed. In the case where an ad-
dress data of the four least significant bits is replied
when a certain group is polled, the program proceeds from
the step S6 to the step S7 wherein it is determined whether
there is a particular combination ~referred to as overlap
in the flow chart) shown in Fig. 6(c) in the address data
of 4 bits being replied. If and when there is no such
particular combination, which means that only one inter-
ruption request signal IRQ is transmitted from only one
terminal included in the group in question, the terminal
is accessed in an individual accessing mode based on only
the address information replied from the terminal and then,
the supervisory data transmitted from the terminal is ac-
cepted in the central controller. Thereafter, in the step
S9, the mode signal M in the transmission signal is set
to an ACK mode signal and is transmitted to the terminal.
Thereafter, the program re-turns to the step S5 and the
subsequent group of terminals is accessed. If and when
all of the group accesses are terminated, the program returns
from the step S5 to the start.
If and when the address data of the four least
significant bits is replied and there is a par-ticular com-
bination as shown in Fig. 6~c) in the replied data, the
program proceeds from the step S7 to the step S10. There-
after, all of the terminals included in the group which
replies the address data of the four least significant
~.`L~;7~
- 21 -
bits are sequentially polled in an individual accessing mode.
More particularly, in the step S10, the transmission signal
is sent out in an individual accessing mode, starting
from "0" of the leas-t significant address indicating an
individual identifying address in the group.
In an operation of a terminal in an individual
accessing mode, -the program proceeds to the steps S102
and S103 in Fig. 11 and, if bo-th addresses coincide with
each other, the program further proceeds to the step S104.
In the step S104, it is determined whether an interruption
flag is set. Since an interrup-tion flag has been already
set in the step SllO, the program proceeds to the step
S113 wherein an interruption status bit is set to 1.
Thereafter, in the step S106, a reply signal is sent out
and in the step S107, the control data is accepted. In
this case, in the central controller 1, the supervisory
data replied in the step Sll in Fig. 10 is accepted and
in the step S12, it is determined whether the interruption
status is set. As described in the foregoing~ since the
interruption status bit was already set to 1 in the step
S113, the program proceeds to the step S13 wherein a neces-
sary control data is produced based on the accepted super-
visory data. Thereafter, in the step S14, the mode signal
M is set to an ACK mode and is transmitted to the terminal.
Thereafter, in the steps S15 and S16, the address defined
by the least significant bits of terminals included in
the group is incremented so that all of the terminals
included in the group are sequentially polled. After
the final terminal included in -the group is polled, -the
sequence returns to -the s-tep S5 and a polling for a subse-
quent group continues.
An operation of the terminals when the terminals
receive a transmission signal in a group accessing mode
in the step S5 will be described with reference to Fig.
11. After a -transmission signal is received in a group
accessing mode in the step S101, it is determined that
;7~i
- 22 -
the mode is not an indiv.idual accessing mode in the step
S102 and thus the program proceeds to the step S114. In
the step S114, it is determined whether the mode is an
ACK mode or a group accessing mode. In this particular
case, the mode is a group accessing mode and hence the
program proceeds to the step S115 wherein both addresses
in the four most significant bits are compared with each
other. If both addresses. coincide with each other, it
is determined whether -the interruption flag is set in
the step S116. Since the interruption flag has been al-
ready set in the step SllO for the purpose of sending
out an interruption request signal IRQ, the program pro-
ceeds to the step S117. In -the step S117, the information
of the four least significant addresses of the terminal
is sent out as a reply signa].
Furthermore, as described in the steps S7 and
S8 of Fig. 10, in the case where a particular group is
identified in such a group accessing mode and the corres-
ponding address data of the four least significant bits
is replied without any particular combination shown in
Fig. 6(c), the terminal replying the address information
in the four least significant bits is accessed in the
individual terminal accessing mode.
Now we will describe such an operation of the
terminal at -that time in the following with reference
to Fig. 11.
In this case, since the mode is an individual
accessing mode, the program proceeds from -the s-tep S102
to the step S103. Then, if both addresses coincide, the
30 program proceeds from the step S103 to the step S10~ wherein
it is determined whether the interruption flag is set.
Since the interruption flag has already been set, the
program proceeds to the s-tep S113 wherein the interruption
status bit included in the reply signal is set to 1 and
thereafter, in the step S106, the reply is sent out and
in the step S107 the control data is accepted. Based
on the reply signal sent out in the step S106, the super-
vlsory data is accepted in the step S8 in Fig. lO. Then,
since the mode signal is set -to an ACK mode and the trans~
mission signal including the same is sent out, -the program
5 proceeds to the step S118 through the steps SlO1, Sl02
and S114 on the side oE terminals receiving -the trans-
mission signal. In the step Sl18, the address is checked.
Since the address remains -the same although the mode signal
is set to be an ACK in the step S9, the result of address
comparison is a colncidence. Accordingly, the program
proceeds to the step Sll9 wherein the set interruption
flag is reset. Thus, af-ter the interruption flag i5 set
and an interruption request signal is sent out r necessary
da-ta communication between the terminal and the central
controller is made and then the interruption flag is im-
media-tely reset, so that the central controller can wait
a next interruption request.
In the above-described embodiment, an interruption
request signal IRQ may be withdrawn at any time point
in a time period designated by an interruption request
signal standing-by period defining signal in the trans-
mission signal. In this respect, in a further preferred
embodiment, such an interruption request signal standing-
by period is equally divided into a plurality of sub-
periods corresponding to the number of groups of terminalsand an interruption request signal to be sent from each
of the groups is adapted to be withdrawn at the timing
of a predetermined subperiod corresponding to the group,
so tha-t -the central controller can easily specify the
group sending an interruption request signal based on
the timing when the interruption request signal is trans-
mitted. Fig. 12A is a waveform showing a timing rela-
tionship in the case where an interruption request signal
standing-by period is equally divided into 16 subperiods.
In Fig. 12A, (a) indicates an interruption request slgnal
standing-by period deEined by the transmission signal,
- 24 -
the standing-by period being equally divided into 16 sub-
periods corresponding to 16 groups of terminals. Each
subperiod corresponds to the address information deter-
mined by the four most significant bits of a terminal
identifying address, that is, an address identifying a
group. For example las shown in (b)), in the case where
an interruption reques-t signal is transmi-tted from the
first group, the four most significant bits of which ad-
dress is "0000", the interruption requPst signal is sent
out at the timing of the subperiod 0, and as shown in
(c), if an in-terruption request signal is transmitted
from the sixth group, the four most significant bits of
which address is "0101", the interruption request signal
is sent out at the timing of the subperiod 5. If there
are interruption requests from the terminals included
in the groups determined by the above-described address
0 and the address 5, pulses appear at the subperiods
0 and 5 and hence a reply signal shown in Fig. 12A(d)
is sent out. In order to send out such interruption re-
quest signal, a signal-to-be-replied output circuit 57
further comprises a circuit shown in Fig. 12B. An in-ter-
ruption request signal standing-by period defining signal
(shown in Fig. 12C(a)) from the signal receiving circuit
51 in Fig. 5 is coupled to one input of an AND gate 570.
Clock signals CK2 as shown in Fig. l~C(b), having a repeti-
tion rate which is predetermined such that one clock signal
is included in one subperiod in the IRS, are applied to
-the other inpu-t of the AND gate 570. An output of the
AND gate 570 is applied to a clock terminal of a counter
30 571. Thus, the counter 571 counts 16 pulses, for example,
during the period of IRS. A clock pulse CK3 as shown
in Fig. 12C(c) is applied to a reset terminal of the counter
571. The output from the counter 571 is applied to a
comparator 572. A group identifying address, which is
determined by the four most significant bits from the
store 59 in Fig. 5, is applied to the other input of the
- 25 -
comparator 572. A coincident output from the comparator
572 is coupled to one input of an AND gate 573. An inter-
rup-tion flag set output from the interruption flag 58
is applied -to the other input of the AND gate 573. In
such a structure shown in Fig. 12B, if and when there
is an interr~p-tion request from a particular terminal,
a corresponding interruption request signal IR~ is sen-t
out at a subperiod corresponding -to a group including
the terminal within an interruption request signal standing-
by period.
Fi~. 13 shows an opera-tional sequence in a central
processor 1 in the case where an interruption request
signal is sen-t out during a predetermined time period
as shown in Fig. 12B. Steps which are particularly dif-
ferent from those described above with reference to Fig.10 are as follows. In the step S131, a group or groups
which are sending interruption request signals are specified
based on the subperiod or subperiods ~or the interruption
request signals sent during an interruption request signal
s-tanding-by period, and a transmission signal is trans-
mitted to these groups in a group accessing mode. There-
after, in the step S132, it is determined whether there
is an overlap of address data in the four least signi-
ficant bits replied as a reply signal. Subsequent opera-
tions are the same as the operations subsequent to thestep S7 in Fig. 10 and hence the detailed descrip-tion
will be omitted.
As a still further embodiment, it is assumed
that it is determined that there is an overlap in the
step 7 in Fig~ 10. ~n overlapped position or positions
in the four least significant bits of a replied address
are de-tected so that possible addresses can be estimated.
For example, in the case where the four bits in the least
significant address are "OODD", wherein D indicates an
overlapped bit position, there are four possible addresses
in the Eour least significant bits, "0000", "0001", "0010"
16~
- 26 -
and "0011". In accordance with these 4 possible addresses,
corresponding terminals can be accessed in an individual
-terminal accessing mode.
As described in the foregoing, if there is an
interruption request from a termlnal, the terminal can
be immediately detected by first using a group accessing
mode and then using an individual accessing mode. Thus,
in the case where a particular terminal is used for the
purpose of crime prevention, an emergency situation seldom
occurs; however, once such emergency situation does occur,
it is necessary -to immediately take the steps necessary
for responding to the emergency situation. The present
system is very useful in such a situation. If a system
is adapted such that a particular terminal which seldom
generates an interruption request signal is not accessed
in a normal time, but is accessed only when such inter-
ruption request occurs, then the availability of the system
can be enhanced.
Although the present invention has been described
and illustrated in detail, it is clearly understood that
the same is by way of i~lustration and example only and
is not to be taken by way of limita-tion, the spirit and
scope of the present invention being limited only by the
terms of the appended claims.
